I Didn't Know That: Building a Mountain Bike

Ooh, mountain bikes, they're so fast! They're so tough, but how do they make them?

These custom built mountain bikes are a rare breed They start at this sheet metal factory where the bikes frames are made out of aerospace grade aluminum.

The templates for the frames are stored on a computer which tells the pressing machine which particular designs to cut out. The aluminum frames are precision welded together by hand, it's this welding that makes the frame strong enough to withstand the constant pounding from riding down mountains, yet light enough to carry across a stream.

Every bike is made to order and uses slightly different geometry depending on whether you ride hard and fast down trails or cool tricks on the streets.

Before it gets painted the frame must be in perfect condition. So any imperfections are sanded off and the dust is blasted away.

Both parts of the frame get a coat of plastic powder paint. And then they're hung in an oven for 10 minutes where the 190 degrees Celsius heat dries them. Then a coat of lacquer goes on and they go back into the oven. A world champion mountain bike deserves nothing less than world class parts and the crème de la crème of bike bits are used on these.

The parts are sourced from all over the world and you get your own dedicated bike builder who carefully assembles it meticulously checking and testing everything from the gears to the brakes.

A basic custom built bike is around £600, but if you want the top of the range model, start saving, it costs £4,000. You could get a car for that.